Production of cyclohexanone oxime



United States Pateti'tOflice 2,111,421 Patented June 21, 1955 2,711,427 I 1 PRODUCTION OF CYCLOHEXANONE OXIME John 1). Christian, Texas City, Tex., assignor to Monsanto Chemical Company,

Delaware No Drawing. Application September 21,1953,

Serial No. 381,471

Claims. cl. 260-566) The present invention relates to the production of cyclohexanone oxime and, more particularly, it pertains to.

the production-of cyclohexanone oxime by the catalytic reduction of nitrocyclohexane.

St. Louis, Mo., a corporation of Cyclohexanone oxime is an important chemical intercatalysts for the hydrogenation of nitrocyclohexane tocyclohexanone oxime, determinedt'hat a silver-containing, oxide-type catalyst was the most selective or specific and gave excellent yields. The catalysts employedmay contain other oxides such as those of zinc and chromium in addition to the silver oxide. t I

I have now discovered that the rate of hydrogenation in the reaction in which nitrocyclohexane is converted to cyclohexanone oxime in the presence of a specific oxidetype catalyst can be significantly increased if an alkaline material is added as a promoter. The alkaline materials suitable for use as promoters are strong bases such as the alkali metal hydroxides, for example, sodium, potassium and lithium hydroxides, the quaternary ammonium bases such as tetramethyl ammonium hydroxide, trimethylbenzyl ammonium hydroxide and the like, and basic salts such as the potassium, sodium, and, ammonium salts of nitrocyclohexane.

Only small amounts of the alkaline promoter are required to speed up the reaction. Quantities ranging from 0.1% to 5% by weight of the nitrocyclohexane fed are generally employed. Preferably, however, amounts representing from 0.5% to 1.0% by weight of the nitrocyclohexane charge are used.

According to the invention, nitrocyclohexane is reacted with hydrogen in a suitable reactor in the presence of an inert organic solvent and a catalyst comprising silver oxide, zinc oxide and chromium oxide and a minor amount of an alkaline material is added to the reaction mixture as a. promoter.

The catalyst suitable for the hydrogenation reaction is prepared as follows:

Silver nitrate (AgNOa-3.4 g), calcium nitrate and zinc nitrate (Zn(NOa)2-6HaO-47 g.), are dissolved in 200 ml. of hot distilled water. A second solution containing ammonium chromate ((NH4)zCr2O-|25.2 g.) and concentrated ammonium hydroxide ml.) in 150 ml. of distilled water is prepared and poured as a fine stream into the first solution with vigorous stirring. The precipitate is immediately filtered, dried by means of suction and heated in a muffle furnace for 1.5 hr. at 350- 400 C. After cooling the product is triturated in a mortar with 2N acetic acid and dried on a suction filter. This treatment is repeated and the product is finally washed'with distilled water and dried at 0. N01

catalyst support is required but if desired a carrier such as pumice, 'clay, alumina, kieselguhr, etc., r nay be used.

The pro'c ess is conveniently carried out in an inert, oxygen-containing organic solvent which is miscible with water. Included among zsuchwsatisfactory solvents are the lower saturated aliphaticalcohols such as methanol, ethanol, and isopropanol, ether, dioxane, t he monomethyl ether of ethylene glycol, the monoethyl ether of ethylene glycol, the monome hyl ether of diethylene glycol, tetrahydrofurane and the like. ferred solvent, however. t n I The' reaction may be conducted at temperatures in the range from 90f C. to -150f C. Preferably, however,. reaction temperature is maintained 'in' ,,the range from r l 15-130' 'C.

Pressures ranging i'rom 500 range provide approximately the same results asthose on the-lower end' of thej'scale,ipressures from 500 pi v to 750 p. s. igare'to be preferred.

.The following examples ,will serve] tojfillustrate j, the

improved process of the invention but areQnot to. be construed as limitative, in any sense, of the invention. I

Approximately 50' ane, '60 mliof methanol and about 2.046 g. of a silver oxide-zinc oxide chromium oxide catalystwere charged to a hydrogenation bomb of'therocker" type. Thesystem= was flushed with hydrogen and hydrogen was then admitted toa pressure of approximately 1600 p. s. i. After several minutes of rocking, an initial pressure reading of 1560 p. s. i. (37 C.) was recorded. The bomb was heated to C. and rocked at this temperature for 11 hours. Final pressure recorded at the end of this period was 850 p. s. i. (40 0.), indicating that 92.8% of the theoretical amount of hydrogen required for the reduction had been consumed.

The liquid reaction mixture from the bomb was warmed and filtered to remove the catalyst. Warm methanol was used to dissolve any of the oxime which had crystallized from the solution and carry it along with the main body of the reaction product. The solution was stripped of methanol and cooled to give an almost solid mass of crystalline cyclohexanone oxime. This mass was broken up and filtered to give a solid mass of oxime crystals. The filtrate was cooled and filtered again to give an added amount of crystalline material. The recovered oxime was washed with very cold petroleum ether (15 cc. chilled to -78 C.) and dried. This material had a melting point of 86-90 C. (Literature value for cyclohexanone oxime 89-90 C). The total cyclohexanone oxime produced was 30.8 g. (0.272 mole) which represents a conversion of 67% of the n itrocyclohexane.

Example I! The experiment described in Example I was repeated except that a small amount (0.465 3. equivalent to 1% of the nitrocyclohexane fed) of the sodium salt of nitrocyclohexane was added to the starting materials in the bomb. The pressure drop was followed after the bomb had reached reaction temperature, by recording pressure measurements at intervals during the hydrogenation. In this case, the reaction was complete in about 4.5 hr., 112% of the thoretical amount of hydrogen required having been consumed in that period of time. The total amount 'of cyclohexanone oxime produced was 31.9 g. (0.282 mole) which represents a conversion of 68% of the nitrocyclohexane.

Methanol is by farthe' pres. i. to 5000 are suitable. Since the pressures on the; highendof .this' ml.2 (0.411 mole) of nitrocyclohex-" 3 Example I-Il consisting of the alkali metal hydroxides, the quaternary The experiment ofE'x'amplc ITi's repeated except that approximately 0.55 g. of sodium hydroxide is substituted for the sodium salt. ofnitrocyclohexane in. the. reaction mixture. charged to. thehydro'genation'bomb. to} "p romote the reaction- A, comparable; yfieldffof eyclohexanone oxime is obtained. and: a comparable accelerating. effecton reactionrate is.observed. H

' Example-JV "Approximately, 50' mt; (0.411 mole) of 'nitr'ocyclohexane, 60 ml. of methanol, about 2105 g. of a silver oxide-zincoxide-chromium oxide catalyst, and. about 0.5 g. of trimethylbenzyl ammonium hydroxide, are charged to a hydrogenation bomb of the rocker'.type and reacted according to the procedure described in Example I. An excellent conversion-of nitrocyclohexane to cyclohexanone oxime is obtained and the reaction rate observed is much accelerated over that of Efxarnglje, I and comparable to the rates obtained in Examples III" What is claimed is p a 1. In a, process for the production. of. cyclohexanone oxime by the hydrogenationoff nitrocyclohfexanein the presence of a silver oxide catalyst'and in an. inert organic solvent medium, theimprovement. which comprises adding an alkaline promotercho'sen' from. thegroup. consisting of the alkali metal hydroxides, the quaternary ammonium hydroxides, and alkaline metal salts in an amount in the range of from about 0.1% to about 5% by-weightof the nitrocyclohexane. fed';

2; In; a process for the production: of cyclohexanone: oxime by the; hydrogenationof nitrocyclohexane in the: presence; of a silver oxide catalyst and in an inert; or-- ganic. solvent: medium, the improvement which comprises, adding an alkalinepromoter chosen from the group.

ammonium. hydroxides, and alkaline metal salts inan amount in the range of from. about 0.5% to about 1.0% by weight of the nitrocyclohexane fed.

3. The process of claim 1 wherein the alkaline prometer is sodium hydroxide.

4. The process of claim- 1 wherein the alkaline promotor;.is trirnethylbenzyl ammonium hydroxide ,v a

syrhepro'ces's of claim 1 wherein the alkaline promotenistliesodiuntsalt-01E nitrocyclohexane: a I e '6. A'process for the production 'of cyclohexanone oxime which comprises reacting nitrocyclohexane with hydrogen in an inert organic: solvent mediumat a, temperature from aboutSfi 6;. ttnabout 150 C. and a pressure from about 500 p. s. i. to 5000 p. s i.,. in the presence of a silver oxidecatalystan'd from"about*0.1% to about 1% by weight of the nitrocyclohexane fed of an alkaline promoter chosen from the group consisting of the alkali metal-hydroxides; the quaternary ammonium hydroxides,

andalkaline alkali metal salts;

' ""7L'ITYIB process oi? claim 6 wherein motor is sodium hydroxide. e

8.'Theprocess of claim 6 wherein'said-alkaline prometer'is-.trimethylbenzyl-iammonium 'hydroxider '9."I-he process of 'claim-- wherein'said alkaline pro motoris thesod'ium salt of nitroeyclohexane;

1 0.- A process-torthe production ofc'yclohexanone ox-ime" which comprises reacting nitrocyclohexane with hydrogen in methanol-at a temperature of about C.

and a pressure of about 750 p. s. it in thepresence ofa si1'ver-oxide'-zinc oxide-chromium oxide catalyst and about l byweight of the nitrocyclohexane fed of the sodium salt of? nitrocyclohexaneas catalyst;

No references: cited:

said alkaline pro a promoter with said 

1. IN A PROCESS FOR THE PRODUCTION OF CYCLOHEXANONE OXIME BY THE HYDROGENERATION OF NITROCYCLOHEXANE IN THE PRESENCE OF A SILVER OXIDE CATALYST AND IN AN INERT ORGANIC SOLVENT MEDIUM, THE IMPROVEMENT WHICH COMPRISES ADDING AN ALKALINE PROMOTER CHOSEN FROM THE GROUP CONSISTING OF THE ALKALI METAL HYDROXIDES, THE QUATERNARY AMMONIUM HYDROXIDES, AND ALKALINE METAL SALTS IN AN AMOUNT IN THE RANGE OF FROM ABOUT 0.1% TO ABOUT 5% BY WEIGHT OF THE NITROCYCLOHEXANE FED. 